IOO 



NA TURE 



\_Dcc. 4, 1 8 84 



It is also, of course, important that the half-dead leaves 

 should hang long on the trees, so as to develop their full 

 colouring before being blown off by the wind. 



Taking thus all the facts into consideration, it appears 

 clear that all the bright and beautiful tints of autumn arc 

 merely the earliest stages of decomposition, and are due 

 to the more or less considerable triumph of chemical 

 forces over the weakened or destroyed vitality of the 

 living plant. One cannot but feel that this is a very 

 unpoetical way in which to regard the magnificent tints of 

 a fine autumnal landscape, but it is no less true than that 

 the coloured clouds of evening mark the departing day. 



H. C. Sorby 



A TORNADO PHOTOGRAPHED 

 T SEND you to-day a photograph of a genuine Dakotah 

 -^ cyclone, or, rather, tornado, which was taken by F. N. 

 Robinson, Howard, Miner County, D.T., August 2S, 1884. 

 The storm passed twenty-two miles west of the city. 

 It was first noticed at 4 o'clock p.m., moving in a south- 

 easterly direction, remaining in sight over two hours ; 

 killing several people, and destroying all property in its 

 course. I believe it to be unique as a portrait of this 

 class of storms, and I have thought you might care to 

 reproduce it for Nature. EDWARD S. HOLDEN 



Washburn Observatory, University of Wisconsin, 

 Madison, November 14 



METEOROLOGY OF MAGDEBURG^ 



THE second report, just published, of the Meteoro- 

 logical Observatory of Magdeburg presents some- 

 special features of interest. The observations with the 

 instruments in more general use are given in very con- 

 venient forms in detail and abstract. 



Magdeburg was one of the first observatories to adopt 

 the barograph of Dr. Sprung, which is certainly one of the 

 best barographs we possess. After the purchase-cost of 40/., 

 the annual outlay in working it and preparing its curves 

 of continuous registration for the lithographer is trifling. 

 The curves are also of high value as accurate representa- 

 tions of the variations of atmospheric pressure. The 

 whole of these curves are reproduced by Dr. Assmann in 

 an elaborate series of lithographs, on which the inch of 

 pressure is on a scale of four inches, and the twenty-four 

 hours of the day extend over five inches and a half. By 

 this large scale the minuter changes of pressure are 

 represented with great distinctness, and their relations to 

 changes of wind, cloud, and other weather conditions can 

 be more clearly seen. Dr. Assmann draws attention to 



1 "Jahrbuch der Meteorologischen Beobachtungcn der Wettenverte der 

 Magtleburgischen Zeitung." Herausgegeben von X)r. R. Assmann. Jahr- 

 ,;rii);ll .383. (Magdeburg, 1884). 



five of the small changes from August 27 to 30 as disturb- 

 ances due to the Krakatoa eruption. 



The hourly values have been taken from these curves, 

 and the means for the months calculated and added to 

 the report. From these means and those of the previous 

 year, a first approximation to the diurnal oscillation of the 

 barometer for this part of Europe is obtained. The result 

 is peculiarly interesting from the transitions it shows in 

 the hourly variations of the summer pressure as compared 

 on the one hand with the variations which occur at the 

 stations of the German Seewarte on the North and Baltic 

 Seas, and on the other with those which occur at places 

 more in the interior of the Continent. Unfortunately for 

 the prosecution of several inquiries raised by these differ- 

 ences, hourly hygrometric observations arc not available 

 from an)' of these first-class meteorological observatories. 



Another interesting feature are the twelve lithographs 

 which represent the continuous registrations of the sun- 

 shine recorder, on the scale of o'4 inch for each hour 

 These lines, which show the sunshine and inferentially 

 the state of the sky in respect of cloud, give valuable 

 information regarding certain hygrometric states of the 

 atmosphere. Hence, with the aid of these and the baro- 

 metric curves, the influence on the diurnal curve of 



